COL6A3 and neoplasm: The mRNA levels for endotrophin in tumour tissues in PyMT/COL6−/−/endotrophin mice were about fivefold higher than those of endogenous levels in PyMT mice, whereas no changes were seen at the level of other COL6 chains (−A1 and −A2) or the remaining mature portion of full-length COL6A3 chain (COL6A3-N) (Fig 2B).